Solids pump applied to coal gasification



Dec. 18, 1956 H. J. OGORZALY 2,774,635

SOLIDS PUMP APPLIED TO COAL GASIFICATION Original Filed Oct. 22, 1949 ASH REMOVAL HENRY J. OGORZALY, INVENTOR.

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A TTORNE Y United States Patent SOLIDS PUMP APPLIED TO COAL GASIFICATION Henry J. Ogorzaly, Summit, N. .L, assignor to Esso Research and Engineering Company, a corporation of Delaware 2 Claims. c1. 302-14 The present invention relates to a method of gasifying carbonaceous solids in a zone of high pressure in conjunction with hydrocarbon synthesis gas production and utilization. More particularly, the invention relates to improvements in the transfer of the carbonaceous solids in a subdivided form from a zone at atmospheric or relatively low pressure to the reaction zone operating, as stated, at a high pressure.

This application is a divisional application of Serial No. 123,070 filed October 22, 1949, now Patent No. 2,704,704, March 22, 1955.

Heretofore and prior to the present invention, it was a matter of record and commercial practice to transfer solids, such as catalysts, from a zone of lowerpressure to one of higher gas pressure .by employing a combination of so-called lock-hoppers or by means of the pressure developed by an elongated vertical column of aerated powdered solids.

Such devices and apparatus are open to many objections, particularly where it is desired to transfer the solids into a zone of relatively high pressure, such as one in which the pressure is 400 pounds per square inch or higher. For instance, lock-hoppers are cumbersome, expensive to manufacture and operate, and introduce substantial added requirements for gas compression. A single standpipe would be of impractical height while the use of a number of standpipes in series involves an extremely delicate balancing of discharge rates.

According to the present invention, solids can be transferred from an open hopper to a reaction zone operating at pressures as high as 400 pounds per square inch and higher, through the device of operating means which are relatively inexpensive to construct and simple to operate.

The ability to feed solids from a low to a high pressure zone is important, for example, where it is desired to produce a hydrocarbon synthesis gas from coal or coke.

volumes of synthesis gas are produced per volume of' oxygen fed to a generator gasifying coal or coke with oxygen-stream mixtures, it is apparent that the volume of gas to be compressed can be very much reduced by operating the gas generator as well as the synthesis unit 2,774,635 Patented Dec. 18, 1956 2 through the column of liquid from the said zone of low pressure to that of higher pressure. A'satisfactory heavy liquid medium for providing a tight gas seal and a high pressure differential is mercury, although others may be used.

An important object of the present invention is to provide means of utilizing a high density liquid of the character indicated to balance a pressure differential of high degree between two zones and to effect the transfer through the high density liquid, of subdivided solid carbonaceous material from a zone of low pressure to a treating zone operating at higher pressure.

Another object'of the invention is to provide a relatively simple and inexpensive means for feeding subdivided carbonaceous solids continuously to a pressurized reaction zone operating continuously, and at the same time preventing gas leakage from the reaction zone.

In the accompanying drawing there is shown a modification of the invention depicted diagrammatically.

Referring to the modification of the invention illustrated, represents an open hopper containing a mass of subdivided carbonaceous material, from which said material may be withdrawn through a line 121 at a rate controlled by feeder 122 which may be a rotary valve as indicated or a non-compression screw or any other suitable feed device. It is not required to build up a pressure differential. In this modification a high density liquid, for example, mercury circulates continuously in the system consisting of lines 123, 124, 125, the elongated vertical receptacle 126, a line 127 and a pump 128. The coal discharged from feeder 122 onto the level of mercury indicated by 12 is continuously entrained by the flowing stream of mercury and carried in suspension through line 125, which discharges into receptacle 126. Receptacle 126 serves as a coal disengaging zone, the coal moving upwardly to the surface of the mercury indicated at 13 because of the buoyant effect ofthe latter. By employing high velocity turbulent flow through line 125, the buoyant eifect is overcome in this vertical column, and the coal particles are caused to How downwards in line 125. In receptacle 126, the upper layer of mercury above the point of introduction of line does not circulate and in the lower section the velocity of the liquid is sufliciently low so that the buoyant effect exceeds the drag on the particles, and they rise as a result.

The carbonaceous material accumulated above the mercury level [3 is forced by the operation of the screw 129 into gas inlet line 135 of gasifier 130. As before, steam generated under pressure from some source (not shown) is introduced into the system through line 135 and passes upwardly therethrough, acquiring the coal or carbonaceous material in suspension. The suspension is then forced into the bottom of gasifier or reactor 130, thereafter passes through a foraminous member G1 into the reactor 130 Where it forms a fluidized. bed of subdivided,

solids in gasiform material by controlling the superficial gasiform velocity. By thus controlling the superficial velocity of the gasiform material and the actual amount of solids therein, the bed will have an upper dense phase level in 130 at a desired level L2. The treatment of the solids with the gasiform material is such as to effect the desired conversion as where carbonaceous solids are treated with steam or steam andoxygen to form water gas. The product is recovered through line 132 from the reactor 130after having first passed through one or more cyclone separators 131 provided with one or more dip pipes 131a, serving to return separated solids to the dense suspension. Oxygen utilized to maintain the desired temperature in 130by causing combustion of some of the carbonaceous material may be introduced into pipe 135 from some source (not shown) through line 133.

The screw for feeding coal from the disengaging zone 126 into the inlet pipe 135 of reactor 130 is preferably of the non-compression type. However, in order to pre vent leakage of steam from the pipe 135 into the barrel of the screw, with which ittisiin communication, .it .is preferable .to force gas .underipressure into: said b'arrel as, forexample, through line :134. In the operation of the system illustrated .air entering with the coal through feeder device 122 will be carried with the coal intodisengaging receptacle 126. Ifdesired, itmay be vented through line 140.

The diiferential in height between mercury levels 12 and I3 provides-the required head of dense liquid to balance the super-atmospheric pressure maintained in reactor 139. Approximately 80 ft. ofditferential height will be required to balance a 475p. s; 'i.. .g. pressure level when mercury is employed as the circulating fluid. It will be appreciated that the pump 12S is'not required to generate a pressure difierential of this magnitude, since liquidfilled column 125 substantially balances column 123. The pump provides only the pressure drop resulting from circulation of the fluid, plus a small added pressure head to compensate for the somewhat lower-density of the fluid and solid mixturein column 125.

Althoughthe examples have referred'to liquid mercury as the confining fluid, other liquids are also suitable, a principal requirementbeing that the fluids should have a high density capable 'ofbalancing the desired pressure by a column of reasonable height. Low melting'poiut metal alloys, such as conventional lead-tin solders, melting at about 350 F. are'suitable. Where normally'solid materials are employed, suitable provision for maintaining temperatures in safe-excess over'the melting point must be provided.

The present invention relates, therefore, generally to transporting carbonaceous material from a zone oflower pressure to one of higher pressureaccording to the'means hereinbefore described in detail, and thereafter treating the thus transported material in the form of a fluidizedbed to yield gasiform material under super-atmospheric pressure.

Many modifications of .theinvention will be apparent to those familiar with the art without departing from the spirit thereof.

What is claimed is:

1. Ina system -for-introducing'solid particles :of relatively low density from a low pressure zone into atreatment zone operating at higher pressure, the combination which comprises a standpipe fora high ;density liquid, means for feeding -said=-solids at low r pressure intothe top of said standpipe, means for circulating a stream'of dense liquid, from a quiescent receiver. zone,;at high velocity into the top of said standpipe and downwardly through the standpipe so as to entrain and carry said particles downwardly with said .streamnotwithstanding .their low density and the buoyant effect .ofrsaid :denselliquid, the quiescent receiver zone connected with .the lower end of said standpipe, wherein .thezparticles are permitted 1 to rise out of said liquidintoaa collectingzone, and an impelling feeder for moving said collected particles transversely into'the treatment zone, the standpipe being of such height and the liquid of such density as to balancethe pressure differential between the' low pressure zone and the treatment zone.

2. System according to claim 1 wherein the particulate solids are carbonaceous material and the'liquid is a metal.

. References Cited in the file of :this patent UNITED STATES 'PATENTS 

